Build a context-free grammar that generates each of the following languages:

Form context-free grammars for parts of the grammar, then use the closure properties of CFGs and CFLs to join them together.

4. Build a context-free grammar that generates each of the following languages: a) aub b) a ba*ba c) U (ab) a*, where (ab) is defined to be (ab)(ab), that is, at least one occurrence of (ab). Form context-free grammars for parts of the grammar then use closure properties of CFGs and CFLs to join them together